^^^Mine didn't need sanding between primer coats, the only imperfections the side covers had were the odd pin hole void on the backside. I sprayed the backside with a paintable undercoating, which filled any pinholes.
The fronts were super smooth, just needed a scuffing for some tooth. I find with spray paint if you do your first coat and let it tack up a couple min you can do a bit of a heavier second coat wet on wet, the second layer will self level a bit and you can eliminate that wet sand between coats. Same with the gloss black, I let it flash and tack up and then hit it wet on wet a few times. You have to be real careful not to get runs but if you pull it off you end up with a super smooth final finish and a nice gloss.
Been doing it this way for years with good results, once you get comfortable with spray paint you can do some great finishes with it. It just doesn't have the durability of anything you can add hardeners too unfortunately.
Oh, Sherman. My in-laws are past Lumby in Cherryville.